It's been around for a long time...at least before I started therapy over 8 years ago.
And discussed quite a bit back when I first started therapy but overall consensus wasn't all that positive.search.php?keywords=nomask

If you find it interesting I would suggest looking at the Tap Pap.https://www.cpap.com/productpage/tap-pa ... roved.html
Not nearly as expensive. I have actually used the TapPap extensively for probably over a year and it's a nice little mask. The mouth guard takes a bit of getting used to but not all that hard.

Chiming in very late here, but I concur with Pugsy that the TapPap does the same thing for less money. However, you do have to have solid and relatively straight teeth, as the mouthpiece molds to your uppers. I'm curious whether the "No Mask" would work better for crooked-toothed people and bridge wearers. They don't give much detail on the website. I do think the "mouth breather" thing can be a red herring. I thought I was a mouth breather before being diagnosed with apnea, but when air is being blown into your nose, you adapt to a different way of breathing, like using a snorkel. Some mouth breathing is probably because you aren't getting enough air, and that's what the masks help you with, whether they cover your mouth or not. I've used a TapPap for about 4 years, no mouth breathing, and it it even works when I have a stuffed up nose from a cold.